hours later -- the final standoff between authorities and the younger brother, dzhokhar when david henneberry climbed up a ladder to look inside his normally shrink wrapped boat. first he saw blood inside of it, then a body. >> my eyes went to the other side of the engine box. the engine box is in the middle -- there's a body. >> reporter: dzhokhar tsarnaev already bleeding before the final shoot-out and surrender. the city on high alert, and henneberry knew he just might be the man police were looking for. and we are learning more, if it can be believed, about what dzhokhar tsarnaev is telling investigators, that the wars in iraq and afghanistan motivated the plot. his claim, there was no outside encouragement, radicalization, or communication that he and his older brother tamerlan were fueled by online jihadist videos. and investigators say he may have consulted al qaeda's english magazine "inspire" for help in building their bombs. investigators also taking a look at an unsolved triple murder from 2011 to determine if tamerlan tsarnaev had anything to do with it. one of the victims a frien